We report on the formation of Ohmic contacts with low resistance and high thermal stability to N-face n-GaN for vertical structure light emitters using a Ti(50nm)/Pt(50nm)/Au(50nm)metal scheme,where the Pt layer is introduced as a blocking layer to suppress the diffusion of Au onto the N-face n-GaN surface.It is shown that unlike the conventional Ti/A1/Ti/Au contacts,the Ti/Pt/Au contacts exhibit an Ohmic behavior with a relatively low specific contact resistivity of 1.1×10^(-4)Ω.cm^(2) even after annealing at 350℃.X-ray diffraction(XRD)measurements by synchrotron radiation and Auger electron spectroscopy(AES)examination are performed to understand the effects of heat treatment.
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